New applications continue to emerge for wireless cellular technology. With these new applications, the importance of supporting higher data rates, lower latency, and massive connectivity continues to increase. For example, support for enhanced Mobile BroadBand (eMBB) communications, Ultra-Reliable and Low-Latency Communications (URLLC) and massive Machine Type Communications (mMTC) have been recommended by the International Telecommunication Union (ITU), along with example usage scenarios and desirable radio access capabilities. With a broad range of applications and usage scenarios, radio access capabilities may differ in importance across the range.
For example, for eMBB, spectral efficiency, capacity, user data rates (for example, peak data rates, average data rates or both), and mobility may be of high importance. For the eMBB use case, the choice of the waveform, as well as the numerology, has the potential to improve spectral efficiency. For URLLC, user plane latency may be of high importance. The choice of numerology may help address this aspect. For example, for Orthogonal Frequency-Division Multiplexing (OFDM)/Discrete Fourier Transform-Spread-Orthogonal Frequency-Division Multiplexing (DFT-s-OFDM) based waveforms, if wide sub-carrier spacing is configured, the OFDM symbol length is shorter, which may help reduce the physical (PHY) layer latency.
For mMTC, the connection density, low device complexity, low power consumption, and extended coverage may be of high importance. The choice of the waveform type and the numerology may address some of these requirements. For example, for systems based on the OFDM waveform, a longer cyclic prefix (CP) may be configured for longer OFDM symbols. This may relax the timing requirements and may allow the use of lower cost local oscillators. For example, longer OFDM symbols may be configured with narrower sub-carrier spacing.